User Logon Failed. the user is not associated with a trusted SQLServer connection. Error: 18452

After installing SQLServer2005 (or the SQLServer2005 that comes with VisualStudio2008), sometimes this happens when you log on with SQL Server Authentication: When You Install SQL Server, the Windows authentication method is restricted. Therefore, an error occurs when a specific user logs on.

After installing SQLServer2005 (or the SQLServer2005 that comes with Visual Studio 2008), sometimes this happens when you log on with SQL Server Authentication: when installing SQL Server, the logon mode is restricted to Windows authentication. Therefore, an error occurs when a specific user logs on.

After installing SQLServer2005 (or the SQLServer2005 that comes with Visual Studio 2008), you can use SQL Server authentication to log on to the Server. Sometimes this occurs:

The cause of this error is that when SQL Server is installed, the logon mode is restricted to Windows authentication. Therefore, an error occurs when a specific user logs on. The solution is as follows:

1. After using Windows authentication, right-click the attributes of the login server.

2. Select "security" to set "Server Authentication" to "SQL Server" and "Windows Authentication mode.

3. Restart the service. OK!